The gunk is normal. All glow engines do the same thing. It is good for the engine. No gunk means something is wrong. Cleaning the plane is something we all have to do.

You may find much better results with 15% nitro for that engine. I don't think you will get the engine to produce the power that it is capable of, or smooth running without at least 15%. Some people try and say that it will run without nitro, but do yourself a favor and give the higher nitro a try.

The two Evos that I have are cold natured. I suggest that you put your finger over the carb intake and turn the prop at least 6-7 times with the throttle set to wide open every time you crank it the first time. After turning the prop, reduce the throttle to idle and gently turn the prop over to ensure that you didn't hydrolock the engine. If hydrolocked, flip the plane upside down and let the excess fuel run out of the muffler. (all of this is done before you attach the glow igniter)

Where is this broken gasket? Do you mean to the muffler?

thanks blwblw, your post was informative. sorry i wasnt more specific about the gasket; yes, its the muffler gasket. I used high-temperature silicone to replace it and it seems to be working fine. I have been priming it, like you said, by cranking it with my finger over the wide-open carb, like the manual says. from now on i'll also check if its hydrolocked.

I'll see if i can get some 15% nitro soon. I have a few questions for you, though. Which evo's do you have? And do their rev's fluctuate above 1/2 throttle? I know i've already said this in my last post, but above 1/2 throttle it sounds like i'm moving the stick up and down when im not and it gets more noticeable the higher it is. I was thinking that this could be some kind of fuel supply problem... or perhaps its not a problem at all with smaller glow engines, because they don't have fuel pumps the fuel supply is never constant?

i was browsing through rcu today and i read something about some people finding their evo's performed better when they moved the needle valve closer to the carb. what do you think about that?

thanks for your help.

If I may interject a thought here....if the engine is changing RPM's up and
down, "like your moving the throttle stick" the setting is WAY TOO LEAN....
and the engine is surging. Usually when it does that, you have to open the
main needle about a 1/4 turn. If the engines is surging, it is overheating as
well, and can be damaged.

If you engine is surging in flight....always chop the throttle....bring the plane
in to land....and readjust the carb to avoid over heating.

FBD.

I have found this same type of contamination in brand new OS and Webra engines. It does not happen often, but often enough to warrant a prerun inspection on all new engines.

Flyboy D, You must have experience with YS engines. ?

Yes I do, but I've not had one surge on me....yet.

FBD.

Hi combatpig,

The poor man's engine cleaner is a very interesting idea! I wouldn't spin a cold engine of the ABC type though, since this would be prematurely wearing it out if it is not fully up to operating temp.

Ernie

Dave, my engine was surging but it was also smoking ... i thought that when it smokes, its too rich.
If it is lean but its still smoking, it might not be burning all the fuel. perhaps i need a new glow plug?

Or maybe its so lean that the smoke is because the parts are wearing down so fast!

I'm really confused with this motor... its supposed to be really easy to run!

Usually when a two stroke aero-motor is surging, it is too lean. Smoke from
the exhaust is not always the best indicator of the fuel/mixture setting. You can
have smoke from the build up of oil in the muffler. You can also have smoke from
a lean condition, causing extra heat in the muffler, burning that build up of oil.....
and fooling you with the look of richness.

For all practical purposes, a good smoke trail is the perfect sign of a happy engine.
Make no mistake about that....smoke comes from the oil burning, not the methanol.

Generally, if a two cycle aero-motor is surging....you should open the high-speed
needle at least 1/4 turn to get it back into the ball park. Some engines lean out
so much in flight, that the initial carb setting necessary for a perfect flight seems irrational....especially to the owner of the plane who has the problems.

As an example.....A Guy had a Sig Wonder with some little .15 in it. The thing would
go about three laps, then die out. I reset the high speed needle with 12 clicks out
for the proper setting....that's darn near a full turn out.

Some engines when set for peak will run for about 10/15 seconds....then lean out.
You have to open the needle 3-4 clicks. Then it does the same thing....peaks out,
runs strong....then wants more fuel.

There are of course....several things that are adding to the equation. The bottom
line is....you have to wait each time you change the carb mixture setting to find
out what the final result will be. If the carb isn't set right....you will know about it
very shortly.

FBD.

If the engine is set with a slightly pre-flight mixture (300-500 rpm down from peak rpm) and then starts surging in flight, like you are moving the throttle, or it is going lean-rich-lean-rich.......

.... there is a 90% chance you have a fuel system problem. Most likely, air bubbles in the fuel or fuel foam.

The air bubbles DO cause it go to lean, then rich when there is no bubble, then lean again - eventually the engine gets hot, and the problem gets worse - then the engine sags and runs like garbage.

1 - Make sure the fuel tank is packed in foam and does not touch any structure
2 - Double check all of the fuel lines (including INSIDE of the tank) to make sure there are no holes or cracks.
3 - Make sure the clunk is attached properly and does not touch the back of tank

Many times you will not see foam or bubbles on the ground. Often it happens in the air when the engine unloads a bit, and creates that perfect 'frequency' to buzz the fuel into a foam.

I hope this is helpful.
Bob

....also check your vent lines for holes and cracks around the ends. Make sure the vent line isn't being shut off by rubbing the top of the tank. For a 2 stroke- check the fuel line running from the HS needle valve to the carb. Sometimes, you won't find the hole in the fuel tubing by looking or forcing air thru it under water. Swap glow plugs just to be sure if the problem remains.

My sport planes (2 strokes) are usually set to be nearly 4 cycling one the ground. They lean out perfectly in the air.

Ernie

I had it running good the other day... i richened the HS needle by 1/4 turn, like FBD said (thanks!) and after that i changed it 1, maybe 2 clicks. as far as i could tell, it was running good! a little smoke, but no surging, almost instant response. I could also idle it at lower than the manual says, but i didnt do it much incase it caused damage.

But of course, with my luck, there came another problem. I was doing the pinch test. the settings seemed okay as per the instruction manual (slight rise in rpm before dying) and i just wanted to test it again. but then it would not start. it seems that its not sucking fuel anymore.

This is what i figured out: I put my thumb over the carb and turned over the prop a few times. (primed it). it looks like the fuel goes in the carb, then is pushed back out, with air bubbles in it. I can also hear a slurping noise. it sounds like its coming from the front ball bearing or somewhere under the carb. So: i took the prop and nut and the thing that the manual calls the prop driver off, plus the little washer between the prop driver and the ball bearing. (just to clarify that i dont have any parts missing, thats all that should be there) Now I was looking at the front ball bearing inside the case. It looks like some fuel dribbled out of the ball bearing. Also, before i took this apart, the bottom of the front of the crankcase was all wet, and im sure it was fuel.
So, as far as i can tell, fuel is leaking out the front ball bearing and air is going in through there, so I have no vacuum to suck fuel in and keep it there. There is a seal on the ball bearing, but it does not cover the crankshaft. I'm wondering if there is a seal on the inside that is perhaps broken? It could also possibly be the gasket for the carb that's leaking, but i dont really think so. Should i take the carb off and check? or do i just take the whole thing into the LHS to get it checked over.

I just want to say, I would rather have someone give advice to me so I can fix it myself, rather than getting the LHS to do it for me, so i can fix it if i have more problems later. Someone told me that if i wanted to do this myself, then i shouldn't be coming to RCU, cause then i'm not doing it myself, but I just want to be familiar with this motor. That's why i prefer to come here than LHS.

Thankyou everyone for bearing with me, I know you must be all shaking your heads at my logic, but I really do want to learn about building and maintaining these planes, not just flying them. thankyou everyone.

Whoever told you that you should do it yourself and not come here is what my country cousins would call "throwed off".

How the hell else are you going to learn? And what's the difference between asking here, and asking another modeler at the field? You're still going to make the adjustment yourself; you just need to to know HOW.

I, for one, applaud your desire to learn as much as you can. In today's world of $100 plug'n'play park fliers, too many hambones with short attention spans are infesting our hobby. They don't want to learn anything; they just want to 'have fun'...

Keep asking those questions. The data base of collective knowledge here is immense.


BTW, I'm not familiar with your Evo engine, so that's why I didn't offer any advice. But it certainly does sound like a leak through the front end. The remedy depends upon whether it is a bushed or a bearinged engine.

couldn't of said it better myself!! i'm not good with words, i think i confuse alot of people alot of times... but what you said is exactly what i was getting at. oh, and thanks for your support, hehe.

Well, it is a bearinged engine... ABC... im trying to think of what else i should say... it has the HS needle valve mounted on the back of the motor... and that is all I can think of.

You need a front bearing that is sealed on one side. That side, of course, goes against the prop thrust washer. There's a difference between sealed and shielded. Shields are designed to keep grease in and dirt out, while still allowing some "migration" of excess grease. Fuel will slip right through.

However, I'd check with Horizon first; there might be something about that engine that precludes use of a sealed front bearing. I cannot imagine what that might be; but you never know. I understand Horizon has replaced a lot of these engines outright. That is a dead give-away that there was a problem and they knew about it. No shot at Horizon; they're usually as good as it gets regarding customer service. My point was that this a new design/production; there are bound to be initial problems.

For anyone who still looks at this thread... my computer crashed after i wrote the last message so i finally got it back now. During that time i went to the LHS... he took a look at it, ran it... says there's no problem!! it must have the shield that Steve Campbell was talking about. I have no idea why fuel wasn't going in the carb, perhaps it's just a side effect that it is hard to prime the motor when it is hot... not sure. but all seems fine, i had it running just fine the other day, planning to put it back in the plane and send it on its maiden voyage the next sunny calm day i see... thankyou all for your support (if you still look at this thread from time to time... heheh) talk to y'all later, and happy flyin

Sorry to get a little off topic, but I was wondering if anyone knows how to set the low speed needle on an evolution 100 engine ? I have a P51 PTS and the needle limiter fell off and I don't know how to set it.

Thanks in advance, Rob

Barwelle,I think your hard to start problem is coming from overpriming.Be careful not to overprime it.Look at the fuel line to carb.When fuel arrives carb when u flip to prime then only one more flip is normally enough priming.Dont bother with the fuel if gets back in fuel line.
Put the glow driver on and flip to start at high idle.I dont think front bearing is a problem for you because no problem for idling of that engine.

I have seen 3 new .46 NTs on GP trainers at our field this year and they all ran flawlessly right out of the box. Even better when the trainer prop is replaced with 10x6s. Can't say anything bad about this engine and am thinking about getting the .61.